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Old Apr 27, 2015, 01:02 PM
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Controlling a hovercraft without a rudder

I bought this 1978 free flight hovercraft on ebay. I'm going to convert old 049 engine to 300 class motor and make it free flight again. But then I started thinking that the fake engine pods could house real motors and maybe be used for steering. I found a 28mm EDF motor/fan that would fit perfectly in them from eflite. So I know I can fit all three motors in the hovercraft. The thing is I have no experience with setting up a receiver to control three motors. One motor on throttle to control altitude and two motors set up on rudder or aileron to control steering by turning on only one of the two motors. It would be a slow turn maybe but at least it would be something and it wouldn't require any noticeable mods to the exterior. BTW I'm knowingly passing on mounting a prop with rudder behind like a swamp boat because again that would ruin the look. Quad copters do this multi-motor thing so I was wondering if my problem is easy or hard to solve?
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Old Apr 27, 2015, 01:45 PM
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What you're talking about is steering with "differential thrust" and it's been used quite a bit in all sorts of craft including hovercraft (that's how the little AeroAce toy planes steer).

It's easy enough to do if your transmitter has the mixing capabilities required. Most modern TXs with 6 or more channels can probably manage it. Not that you need all the channels, it's just that TXs with less channels usually have no controllable mixes. You want mixing so that you can control the forward speed as well as the direction.

Steve
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Old May 05, 2015, 11:44 AM
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What tx do you have? Plug it into google with the term 'differential thrust' and you'll find out how to mix it.

Differential thrust works great, and you don't need much if the nozzles are spaced wide enough.

Go for it!
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Old May 05, 2015, 01:18 PM
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If you're stuck with a very basic tx that doesn't offer mixing, you can get differential thrust using a V-tail mixer and two normal channels (throttle and direction). There's a few quirks to using one of those but it does work.
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Old May 05, 2015, 06:08 PM
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Or, if you're stuck without a mixing radio or v tail mixer, put the left edf on the throttle channel and the right one on the aileron stick, you can then use both sticks, push both up and let off on one to turn that way, like driving a hover-tank, hehe!
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Old May 08, 2015, 06:51 PM
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I have a Multiplex Royal Evo 12 so I can do any kind of mixing I want.
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Old May 08, 2015, 06:55 PM
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So I've ordered parts and I have them all in and I've started construction of the modifications. Turns out that a 28mm fan fits perfectly inside the engine nacelles so I ordered two eFlite EDF fans and motors. These will make it go forward and turn. I bought a 1000k/v 400 motor to lift it off the ground.
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Old May 08, 2015, 09:52 PM
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Looks like a fun project. I remember having this model years ago and was fascinated how well it hovered without a skirt, especially when i removed the dummy engines to save weight.
Be interesting to see how well it works with the mods you are doing - i bet you will end up modifying the hull as well to improve lift as its not a very efficient design -but looks great anyway.
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Old May 09, 2015, 10:39 AM
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Cool! Keep it coming!
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Old Jun 09, 2015, 07:06 PM
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Great model to have for it!!
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Old Jun 10, 2015, 12:30 AM
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I'm on my third motor. First one not strong enough. The second overheated. Hope the third is the right one.
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